Bad results due to left joins

Question

I am trying to get all my post where Vote IPAddress doesnt match mine own. Here is my SQL. The problem is, i get the post i voted for when someone else also voted for it. I thought this code says select post when left join is possible and there are no IPAddr which == mine. But that doesnt seem to be happening. How do i write this?

select * from Post 
left join Vote as V on V.post=Post.id AND V.IPAddr<>123
where flag='1';

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Here is some dummy data to illustrate the problem.

create table P(id int primary key, body text);
create table V(id int primary key, val int, ip int, post int);
insert into P values(1,"aaa");
select * from P left join V on V.post=P.id where (V.ip is null or V.ip<>123);
insert into V values(1, 2,123,1);
select * from P left join V on V.post=P.id where (V.ip is null or V.ip<>123);
insert into V values(2, 2,13,1);
select * from P left join V on V.post=P.id where (V.ip is null or V.ip<>123);

Answer 1

select * 
from Post p 
left join Vote as V on V.post=p.id 
where (V.IPAddr is null or V.IPAddr<>123) 
    and flag='1'; 

Update:

select * 
from P 
left outer join V on V.post=P.id 
where not exists (
    select 1 from v
    where IP = 123
    and post = p.id
)

Answer 2

Perhaps something like...

SELECT *
    FROM P
    WHERE EXISTS (SELECT *
                      FROM V
                      WHERE V.IP IS NOT NULL AND
                            V.IP <> 123      AND
                            P.ID = V.POST);

is what you are looking for.

Answer 3

Is this what you need?

SELECT * FROM P 
WHERE NOT EXISTS
     (SELECT * FROM V 
      WHERE V.post=P.id AND V.ip=123)